1. Field of the Invention
The invention relates to apparatus for recording and/or playing back magnetic recordings of high frequency, in particular video signals, on a recording tape accommodated in a cassette, which apparatus is provided with a tape guide drum along which the tape is passed in a helical path (hereinafter referred to as a helical scan cassette recorder); and more particularly to a helical scan cassette recorder having a self-threading device, which includes a support rotatable about a spindle and at least one tape guide element mounted on the support. Upon insertion of a cassette into the apparatus the guide element projects through an opening of the cassette behind the tape which extends near this opening. When the support is rotated, the tape is positioned around the drum by the guide element. Such apparatus also has a motor-driven capstan which functions as a tape drive spindle, projecting through the cassette or located near the drum.
2. Description of the Prior Art
An apparatus of this type is known from Netherlands Patent Specification No. 142,004 to which U.S. Re-issue patent No. RE 28,215 corresponds. In this known apparatus the capstan and its drive motor are at a fixed location. After the tape has been wound around the drum by rotation of the support, a movable pressure roller is biased toward the capstan, the tape being gripped between the capstan and pressure roller. This provides reliable tape driving at normal speeds. However, because the tape spools are mounted coaxially, rapid winding can most effectively be carried out only over the drum; this winding mode is a relatively complicated function.
To provide the advantages of easy high speed winding, and less wear while operating in that mode, another known apparatus having cassette reels coplanar rather than coaxial is disclosed in U.S. Pat. No. 3,969,766. This advantage is obtained at the expense, however, of a substantially more complex tape threading device.
A drawback of the known helical scan cassette recorders is that the course of the tape in the apparatus--whose accuracy influences the recording/playback quality and the interchangeability of cassettes and equipment--depends on components which are movable relative to the frame, such as the tape guide pin(s) which are disposed on the rotatable support, and on components which are disposed at a fixed location in the frame, such as the capstan. Designs of this type require very tight manufacturing tolerances, so they have high manufacturing costs.